[kazinator]

If it exists in the version I'm using, it is certainly not discoverable. I don't see any hint of this in a two-level-deep manual search of various menus. I would expect to find osmething like this if I right click on the toolbox (context menu pops up, with one of the choices being "Add New Preset ..." or whatever). Or in the Tools menu, with a menu item being "Manage presets ..." or whatever.

Ah, finally found it. You have to click on the little docking triangle on some specific Tool Options dialog for a given tool. It is in this docking-related menu that a command is found to bring up the Tool Options Menu! I think I didn't notice it before because it's totally "off topic" for docking. (Why would a semantically important feature be found under a little docking triangle?) It is this Tool Options Menu which has the preset management commands.

If you right click anywhere on the Tool Options, you get context menu with one-button context menu which says "Tool Options". When you click that button, it just disappears: there you are in Tool Options as before! Right clicking on a Tool Options object would be the obvious place to have the Tool Options Menu. Then the preset stuff would be more discoverable.